This invention relates to a light-emitting display device.
Display devices using light-emitting diodes, liquid crystal display devices, or organic EL (electro luminescence) devices as a light modulation layer of a pixel are apt to expand their application ranges in addition to display devices such as business machines and computers primarily because the display units can be thinned. Among these display devices, a light-emitting display device using organic EL devices has the following advantages compared with a liquid crystal display device (LCD).
(a) Since the organic light-emitting display device is of a self-emission type, a clear display and a wide viewing angle can be obtained. Further, low power consumption, lightweight, and thin thickness can be realized because no rear light source is necessary.
(b) The response speed is fast. The response speed of organic light-emitting display device is on the order of microseconds (xcexcs) while that of an LCD is on the order of milliseconds (ms).
(c) Since a solid luminous layer is used, there is the possibility that the working temperature range may be wider.
On the basis of these advantages, research and development of organic light-emitting display devices have been promoted actively. Particularly, there have been carried out those of a polycrystalline silicon thin film transistor (p-Si TFT) type organic self-emission display system. Pixels of this display system are disposed in a matrix form and each connected p-Si TFTs for driving the display device so that such a display system can realize high resolution.
FIG. 10 shows schematically a cross-sectional view of an array substrate in a conventional organic light-emitting display device. An organic thin film layer including at least an organic luminous layer 113 is held between an anode 109 and a cathode 115. When an energizing voltage is supplied between the anode and the cathode, electrons and holes are injected into the organic thin layer where they are recombined. Thus, exciters are generated in the organic thin layer. Light is emitted from the organic thin layer when the exciters lose energy by transferring from a higher energy level to a lower one.
The organic light-emitting display device, as shown in FIG. 10, has an opening above the anode 109 and a and a driving TFT. The driving TFT includes a p-Si layer 103, a gate insulating film 104, a gate electrode 105, and source and drain electrodes 107. A passivation film 110 and a partition insulating film 111 are formed over the p-Si layer 103, gate insulating film 104, gate electrode 105 and source and drain electrodes 107.
The luminous intensity of such a conventional organic light-emitting display device is about a half of the luminous intensity (100 to 150 nt) of the LCD. Further, cross-talk occurs between neighboring pixels. Where, in particular, the color of red (R), green (G), or blue (B) is emitted from the pixel, colors from neighboring pixels are mixed so that the contrast of the organic light-emitting display device is considerably lowered.
An object of the present invention is to provide a solution for the aforementioned problem.
An object of the present invention is to provide a light-emitting display device with improvement of the output efficiency of light from the light-projecting surface.
Another object of the present invention is to suppress the occurrence of cross talk between neighboring pixels.
A first aspect of a light-emitting display device in accordance with the present invention includes pixels which are provided with a plurality of first electrodes electrically isolated from each other; second electrodes provided opposite to the first electrodes; a plurality of pixels held between the first and second electrodes; and a light-reflecting surface disposed between adjacent ones of said pixel electrodes.
The pixels are disposed in a matrix form and each have at least a light-emitting layer. One of the first and second electrode defines a light-projecting surface. The light-reflecting surface transmits light traveling from one of the adjacent pixels toward the other thereof to the light-projecting surface.
A second aspect of a light-emitting display device in accordance with the present invention further includes partition insulation films to electrically isolate the first electrodes from each other. The partition insulation films define openings between the adjacent pixels. The other of the first and second electrodes provides opposite to the light-projecting surface via the luminous layer includes inclined surfaces provided along the partition insulation films. The inclined surfaces are used for the light-reflecting surfaces and define an acute angle with respect to the light-projecting surface.
A third aspect of a light-emitting display device in accordance with the present invention is characterized in that the second electrodes are continuously formed on the pixels.
A fourth aspect of a light-emitting display device in accordance with the present invention is characterized in that the inclined surfaces are formed around the pixels.
A fifth aspect of a light-emitting display device in accordance with the present invention further includes partition insulation films to electrically isolate the first electrodes from each other. The partition insulation films define openings around the pixels. The second electrodes are provided to cover the partition insulation films and include inclined surfaces at the openings which define an acute angle with respect to the light-projecting surface.
The above-stated and other objects and advantages of the invention will become apparent from the following description when taken with the accompanying drawings. It will be understood, however, that the drawings are for purposes of illustration and are not to be construed as defining the scope or limit of the invention, reference being had for the latter purpose to the claims appended hereto.